I have a prefab Bookcase from IKEA with adjustible hinges. I am having problem leveling the glass door. Any suggestions?

Pe-fab stuff usually comes with pre-drilled holes for mounting the doors, hardware, etc. They are not neccessarily pre-drilled in the right places, however. You may have to re-drill the pilot holes so the door will hang correctly. Get someone to help you hold the door where it should go and mark the hinge holes for drilling. Then remount the hinges to the door and install the screws.